ATT Iphone 7 Plus

I recently had a rsim11 on my att iphone 7 plus that was working on the tmobile network it worked fine until one day it reset by accident nothing would work and was stuck on the activation required screen. I had to buy rsim12 and new tmobile sim card. Well now it will work for a few hours then i get sim failure pop up and after that it says invalid sim on top left corner. I have to turn on and off the phone in order to get data and stuff to work again. Anyone experience this type of issue? And how dis you fix it?

Thanks